Parents should not put ham or salami in their children's packed lunches because processed meat increases the risk of developing cancer, experts in the disease are warning.
The World Cancer Research Fund (WCRF) wants families to instead use poultry, fish, low-fat cheese, hummus or small amounts of lean meat as sandwich fillings when making up school lunchboxes.
Children should avoid eating processed meat altogether because unhealthy habits acquired while young can have serious consequences later, said the WCRF.
"Including sandwich fillers such as ham and salami could mean children get into habits that increase their risk of developing cancer later in life," the charity said.
"It makes sense for children to adopt a healthy adult eating pattern from the age of five. WCRF advises it is best to avoid it [processed meat] as well as many of the habits we develop as children last into adulthood."
If everyone ate no more than 70g of processed meat – the equivalent of three rashers of bacon – a week, about 3,700 fewer people a year in Britain would be diagnosed with bowel cancer, according to the WCRF.
In 2007 the charity there was convincing scientific evidence that consumption of processed meat increases the risk of bowel cancer. Although research had only studied its impact on adults, children should avoid it too, said the WCRF.
Marni Craze, the charity's children's education manager, said: "If children have processed meat in their lunch every day then over the course of a school year they will be eating quite a lot of it. It is better if children learn to view processed meat as an occasional treat if it is eaten at all."
The charity also wants parents to avoid giving their children high-fat or high-calorie foods in their packed lunch, such as sugary drinks, because they could help make them overweight. Excess weight is increasingly viewed by scientists as a major contributory factor to cancer after smoking.
Some high-energy products are promoted as ideal for children's lunchboxes, it points out. For example, Sainsbury's has Peperami in the lunchbox section of its website, despite the product containing 44% fat.
John Bullock, of BPEX, which represents British meat producers, said: "The amounts of these products in children's lunchboxes will be very small. The WCRF's global study in 2007 said there may be a link between eating processed meat and the risk of cancer, but we need more scientific evidence to tell us definitely whether or not that's the case.
In a separate study published today, Cancer Research says widespread ignorance about the symptoms of cancer is contributing to people dying of the disease.
One in seven people in Britain (14%) could not name a single sign of cancer and only small numbers of people named moles (16%), weight loss (16% of men and 22% of women), skin problems (25%) and bowel, urinary or toilet difficulties (19%), the charity found. In a poll of 3,947 people, 54% identified a lump as a being a possible indicator of cancer.
Sara Hiom, of Cancer Research, said up to 5,000 cancer deaths a year could be avoided if cancers were diagnosed earlier. The charity is working with the Department of Health on a major project to improve people's chances of surviving cancer through earlier diagnosis, by increasing public awareness of signs and symptoms of the disease.
"We're not expecting people to be able to recall every symptom, but being generally aware of changes that could be a sign of cancer could make a crucial difference for people who do develop the disease," said Hiom.
